add overlay

flake.nix

@@ -35,6 +35,7 @@
         mkShell {
           inherit buildInputs nativeBuildInputs;
         };
+
       packages.${system} =
         let
           src = lib.fileset.toSource {
@@ -56,5 +57,16 @@
         {
           default = pkgs.callPackage ./package.nix { inherit src buildInputs nativeBuildInputs; };
         };
+
+      overlays = {
+        default = self.overlays.dwl;
+        dwl = final: prev: {
+          pkgs = prev.pkgs ++ [
+            (dwl-final: dwl-prev: {
+              dwl = dwl-final.callPackage ./package.nix { };
+            })
+          ];
+        };
+      };
     };
 }